1. Field of the Invention
The present invention relates generally to treating diseases with immunotoxins.
2. Description of the Prior Art
In the field of treating diseases with immunotoxins, an ongoing problem has been to insure that the immunotoxins kill target cells and only target cells. As described in Frankel et al., xe2x80x9cMeeting Report: Advances in Immunotoxin Biology and Therapy: A Summary of the Fourth International Symposium on Immunotoxinsxe2x80x9d in Cancer Research 56 (Feb. 15, 1996), pp. 926-932, in the case of immunotoxin treatments for cancer there are few treatments which can deliver an effective amount of a toxin to a cell and, and the toxicities which result from the treatments have generally been less than those for conventional chemotherapy.
In one aspect, the present invention provides a heat shock protein immunotoxin comprising: at least a fragment of a heat shock protein, the fragment being capable of being bound by an immune cell; and a toxin bound to the fragment.
In a second aspect, the present invention provides a method for reducing the number of at least one type of immune cells in an individual comprising the step of administering a heat shock protein immunotoxin to an individual in an amount sufficient to decrease the number of immune cells of at least one type in the individual, the heat shock protein immunotoxin comprising at least a fragment of a heat shock protein, the fragment being capable of being bound by an immune cell; and a toxin bound to the fragment.
In a third aspect, the present invention provides a method for reducing the number of at least one type of immune cells in an organ comprising the step of administering a heat shock protein immunotoxin to at least a portion of an organ in an amount sufficient to decrease the number of immune cells of at least one type in the organ, the heat shock protein immunotoxin comprising at least a fragment of a heat shock protein, the fragment being capable of being bound by an immune cell; and a toxin bound to the fragment.
For the purposes of the present invention, the term xe2x80x9ctoxinxe2x80x9d refers to any chemical or substance which kills cells, renders them inactive or causes them to be unable to perform their normal functions. Examples of such toxins include ricin, saporin, Shiga toxin, Pseudomonas exotoxin, radioactive isotopes (either alone or as part of a molecule), etc. Toxins suitable for use with the present invention may also include chemotherapeutic agents such as: bleomycin, methotrexate, cyclophosphamide, vinca alkaloids, adriamycin, cisplatin, etoposides, etc.
For the purposes of the present invention, the term xe2x80x9cheat shock protein immunotoxinxe2x80x9d refers to heat shock protein-peptide complexes where the peptide is a toxin, immunotoxins in which a heat shock protein or a fragment of a heat shock protein is covalently bound to a toxin, and immunotoxins in which a heat shock protein or a fragment of a heat shock protein is combined with a toxin comprising a protein oligonucleotide sequence or molecule.
For the purposes of the present invention, the terms xe2x80x9cbindxe2x80x9d and xe2x80x9cbindingxe2x80x9d refer to both covalent and non-covalent binding.
For the purpose of the present invention, the term xe2x80x9cfragmentxe2x80x9d can refer to a portion of a heat shock protein or an entire heat shock protein.
For the purposes of the present invention, the term xe2x80x9coligonucleotidexe2x80x9d refers to any oligonucleotide, including double and single-stranded DNA, RNA, PNAs (peptide nucleic acids) and any sequence of nucleic acids, either natural or synthetic, derivatized or underivatized.
For the purposes of the present invention the term xe2x80x9cpeptidexe2x80x9d refers to all types of peptides and conjugated peptides including: peptides, proteins, polypeptides, protein sequences, amino acid sequences, denatured proteins, antigens, oncogenes and portions of oncogenes.
For the purposes of the present invention the term xe2x80x9cindividualxe2x80x9d refers to either an individual person or animal from whom a cell lysate, heat shock protein, or peptide is obtained or an individual patient who is treated according to a method of the present invention.
For the purposes of the present invention, the term xe2x80x9cimmune cellsxe2x80x9d refers to B lymphocytes, T lymphocytes, antigen presenting cells, macrophages, monocytes, natural killer cells, and dendritic cells.
For the purposes of the present invention, the term xe2x80x9cantigen presenting cellsxe2x80x9d refers to B lymphocytes, macrophages, and dendritic cells.
For the purposes of the present invention, the term xe2x80x9corganxe2x80x9d is used in the broad sense of this term to include such organs as the skin, bone marrow, etc.
The present invention provides a method for specifically destroying or inhibiting cellular function of immune cells which bind heat shock proteins or portions of heat shock proteins.
Heat shock proteins (HSPs) which are non-covalently bound to peptides as HSP-peptide complexes have been shown to be capable of inducing T-cell mediated responses to tumor antigens, see for example Udono et al. xe2x80x9cHeat shock protein 70-associated peptides elicit specific cancer immunityxe2x80x9d in Journal of Experimental Medicine (1993) 178: 1391-1396; and Tamura et al. xe2x80x9cImmunotherapy of tumors with autologous tumor-derived heat shock protein preparationsxe2x80x9d in Science (1997), 278:117-120. HSP-peptide complexes have also been shown to be capable of inducing T-cell mediated responses to viral antigens as described in Roman et al., xe2x80x9cSynthetic peptides non-covalently bound to bacterial HSP 70 elicit peptide specific T-cell responses in vivo in Immunology (1996), 88:487-492. HSPs covalently bound to antigens as fusion proteins have also be shown to elicit a T-cell specific response, see for example, Suzue, xe2x80x9cHeat shock proteins as vehicles for antigen delivery into the major histocompatibility complex I presentation pathwayxe2x80x9d in Proceedings of the National Academy of Sciences (1997), 94:13146-13151. HSPs have also been shown to be important in the recognition structure for NK cells, see for example Multhoff et al., xe2x80x9cHeat shock protein 72 on tumor cells: a recognition structure for NK cellsxe2x80x9d in The Journal of Immunology (1997), 158:4341-4350 and gamma delta T-cells, see for example Wei et al., xe2x80x9cInduction of autologous tumor killing by heat treatment of fresh human tumor cells: involvement of xcex3xcex4 T cells and heat shock protein 70, in Cancer Research (1996), 56:1104-1110.
Toxins linked to antibodies have been used to specifically target cancer cells as described by Siegall et al., xe2x80x9cImmunotoxins as cancer chemotherapeutic-agentsxe2x80x9d in Drug Development Research, v. 34(#2), (Feb. 1995), pp. 210-219. Toxins have also been linked as a fusion protein to human granulocyte-macrophage colony-stimulating factor by Burbage et al., xe2x80x9cRicin fusion toxin targeted to human granulocyte-macrophage colony-stimulating factor-receptor is selectively toxi to acute myeloid-leukemia cellsxe2x80x9d in Leukemia Research, v. 21 (#7), (Jul. 1997). pp. 681-690; and Frankel et al. xe2x80x9c112 fused to lectin-deficient ricin is toxic to human leukemia -cells expressing the 112 receptorxe2x80x9d in Leukemia, v. 11(#1), (Jan. 1997), pp. 22-30.
However, no one has investigated the possibility of using heat shock proteins as cell-specific carriers of toxins and agents capable of inhibiting the cellular function of immune cells. Since HSPs appear to be recognized by a variety of immune cells, toxin or cellular pathyway inhibitors linked to heat shock proteins may be a very useful tool.
The present invention relies on the fact that heat shock proteins are recognized by numerous cells in the immune system. The cells that are known to respond in the presence of heat shock proteins include T-cells, macrophages, dendritic cells, and B-cells. The toxin linked heat shock proteins of the present invention may provide a means to deplete these cells in circumstances where it is desirable to do so. Although it is not clearly understood at the present time which cells react to specific heat shock proteins, it is conceivable that individual heat shock proteins could be used to knock out specific sub-groups of immune cells.
Suitable heat shock proteins for the present invention include the heat shock proteins listed n U.S. Pat. No. 5,747,332. These HSPs include: members of the hsp60family, hsp70 family, hsp90 family and the hsp104-105 family. Members of the hsp60 family include hsp60, hsp65, rubisco binding protein, and TCP-1 in eukaryotes; and GroE1/GroES in prokaryotes; Mif4, and TCP1alpha and beta in yeast. Members of the hsp70 family include DnaK proteins from prokaryotes, Ssa, Ssb, and Ssc from yeast, hsp70, Grp75 and Grp78(Bip) from eukaryotes. Members of the hsp90 family include hsp90, gp96 and grp94. Members of the hsp104-105 family include hsp105 and hsp110.
Potential toxins which may be used in the complexes of the present invention include ricin, saporin, bryodin, Diptheria toxin and Pseudomonas exotoxin. Immunotoxins which may be used in the present invention""s cancer therapeutic-agents have been described in Siegall et al., Drug Development Research, v. 34(#2), pp. 210-219 (Feb. 1995), the entire disclosure and contents of which is hereby incorporated by reference. The heat shock proteins of the present invention may also be used to deliver toxins such as specific inhibitors of cellular processes such as inhibitors of signal transduction, ion channel function, etc.
Another use of the heat shock protein immunotoxins of the present invention is to deliver chemotherapeutic agents to target cells to treat conditions such as cancer, autoimmune diseases, asthma, etc. One of the advantages using the heat shock protein immunotoxins of the present invention over prior chemotherapy treatments is that using the immunotoxins of the present invention allow for chemotherapeutic agents to be delivered to specific target cells. Because the immunotoxins of the present invention allow for the delivery of the chemotheropeutic agents to specific target cells, the amount of chemotherapeutic agent used in the methods of the present invention may be greatly decreased when compared to conventional chemotherapy treaments, thus avoiding the numerous systemic side effects associated with conventional chemotherapy treatments.
In the complexes of the present invention, the toxins may be non-covalently linked to the heat shock proteins either as peptides (in the peptide binding grooves of individual HSPs), covalently linked to the HSPs, or by the construction of a fusion protein.
Some of the methods which can be used to non-covalently link toxins which are peptides to heat shock proteins as part of an ADP-HSP-peptide complex are described in U.S. Pat. No. 5,747,332, the entire disclosure and contents of which is hereby incorporated by reference. By adding an appropriate peptide toxin to an ADP-column containing a particular heat shock protein bound to the ADP in the column, the peptide toxin will bind to the ADP-heat shock protein complex. The resulting ADP-heat shock protein-peptide toxin complex may then be eluted by running a solution containing ADP through the column.
Methods which can used to covalently link toxins to HSP include methods such as those described in U.S. Pat. Nos. 4,714,759 and 5,645,836, the entire disclosure and contents of which are hereby incorporated by reference.
In making a fusion protein, heat shock protein DNA sequences or fragments of heat shock protein DNA sequences may be combined with toxic protein DNA sequences or molecules using techniques known in the art. Fusion proteins containing sequences of both heat shock proteins or heat shock protein fragments and toxins can then easily be created. Methods which can be used to link toxins to HSP as part of a fusion protein include methods such as those described in U.S. Pat. No. 5,696,237, the entire disclosure and contents of which is hereby incorporated by reference.
The toxin-linked heat shock proteins complexes of the present invention are particularly useful for treating auto-immune diseases, diseases where the immune system attacks self proteins. The complexes of the present invention may also be used to temporarily debilitate an individual""s immune system before and after transplanting an organ. In addition, the complexes of the present invention may be used to inhibit specific intracellular pathways of immune cells. In general, the present invention is useful to treat diseases where it is desirable to reduce the effectiveness of an individual""s immune system.
The heat shock protein immunotoxins of the present invention may be used to kill antigen presenting cells (APCs) and other immune cells having receptors which bind at least a portion of a heat shock protein. The immunotoxins of the present invention may also be useful in treating diseases such as psoriasis. Lupus, or other diseases and autoimmune diseases in which APCs, or other immune cells with receptors which bind at least a portion of a heat shock protein, mediate an inappropriate immune response.
The heat shock protein immunotoxins of the present invention are particularly useful for treating auto-immune diseases, diseases where the immune system attacks self proteins because the immune system mistakes self-proteins for bacterial proteins. The immunotoxins of the present invention may also be used to temporarily debilitate an individual""s immune system before and after transplanting an organ. The heat shock protein immunotoxins of the present invention may also be useful in depleting APCs in transplanted organs to increase the chance that the organ will not be rejected, see Seminars in Immunology (1998), 10:399. In addition, the complexes of the present invention may be used to inhibit specific intracellular pathways of immune cells. In general, the present invention is useful to treat diseases where it is desirable to reduce the effectiveness of an individual""s immune system.
The immunotoxins of the present invention can be administered in any conventional way for treating individual with a drug such as by injecting a solution containing a immunotoxin of the present invention into an individual""s bloodstream, topically applying a solution containing a immunotoxin of the present invention on a particular part of a tissue or organ. For example, a solution containing the immunotoxin may be applied to the skin of a patient suffering from psoriasis. When the immunotoxins of the present invention are used to treat organs which are to be transplanted into an individual, a immunotoxin of the present invention may be topically applied to the organ, the organ may be immersed in a solution of the immunotoxin, or the organ may be treated with perfusion techniques prior to the transplantation procedure. In perfusion, an organ is treated with a solution by using the blood vessels associated with the organ to administer the solution throughout the organ.